G.f.: Sum_{n>=0} 3^n * x^n / (1-x)^(2*n+1) * [Sum_{k=0..n} C(n,k)^2 * x^k]^2.
A246539
G.f.: Sum_{n>=0} 3^n * x^n / (1-x)^(2*n+1) * [Sum_{k=0..n} C(n,k)^2 * x^k]^2.
Terms
- a(0) =1a(1) =4a(2) =25a(3) =184a(4) =1489a(5) =12796a(6) =114241a(7) =1047568a(8) =9796057a(9) =92989876a(10) =893250193a(11) =8663461000a(12) =84697699297a(13) =833616713164
External references
- oeis: A246539